The invention relates to agricultural seeders, such as hoe openers and seeding tools used in farming operations to distribute seeds into a soil.
Generally, precision hoe openers are mounted to the frame of an implement which is towed behind a tractor. These openers may include a ground engaging tool that opens the soil, providing a path for seed deposition into the soil. After the send is deposited, the ground engaging tool may be followed by a packer wheel that packs the soil on top of the deposited seed. The packer wheel may be rigidly mounted behind the ground engaging tool via a structural member or rear frame. Thus, the ground engaging tool and packer wheel generally move together with the same upward and downward motion. This vertical motion, somewhat independent of the implement frame, allows for more precise placement of seed in the soil.
Unfortunately, existing precision hoe openers do not adequately address the need for height variation over terrain during seeding, or for transportation when not seeding. It is generally undesirable to pull the hoe opener through soil when merely transporting the opener from one location to another. In addition, during seeding, existing precision hoe openers do not provide adequate vertical motion of the opener and related assembly without compromising the load on the ground engaging tool and packer wheel. As a result, variations in the terrain can result in drastic changes in the packing force (e.g., normal force) of the packer wheel on the terrain being seeded by the opener assembly and, also, the draft force of the terrain on the ground engaging tool. In turn, this variation in ground opening force and packing force can result in non-uniform seeding depths and packing density in the terrain being seeded.
The distance between the packer wheel and ground engaging tool can also affect the seeding accuracy of the opener assembly. Existing precision hoe openers have a fixed distance between the packer wheel and ground engaging tool. A greater distance between the components will cause variations in the terrain to greater affect on the accuracy of the product placement. As the position of the ground engaging tool is determined by the packer wheel the greater the distance from the packer wheel the less accurate the seed placement. This will also result in non-uniform force applied to the soil by the two components, which reduces seeding accuracy.
For instance, some existing opener assemblies may employ a parallel linkage to control the height of the packer wheel and ground engaging tool. One of the difficulties in using a parallel linkage is that the force at the packer wheel will fluctuate as the draft force is applied to the ground engaging tool as the opener assembly moves vertically relative the carrier frame as the packer wheel follows the contour of the terrain. However, if the packer wheel is too close to the ground engaging tool there may be insufficient time for the soil displaced by the ground engaging tool to flow back over top of the seed prior to the packer wheel packing the soil down. Therefore there exists an optimal distance between the packer wheel and the ground engaging assembly that is small enough to provide accurate contour following by the opener assembly and large enough to allow for the soil to flow back over the seed prior to being packed by the packer wheel. It would be desirable to be able to adjust the position of the packer wheel relative to the ground engaging tool to optimize this distance for a given field condition.
Existing precision hoe openers also require substantial force to raise the opener assembly, including the ground engaging assembly and packer wheel. This requirement results in the use of large hydraulic cylinders to raise the apparatus, due to the overall length and weight of each opener assembly. This hydraulic equipment is costly and takes resources (i.e. hydraulic power) from other portions of the tractor and seeding implement.
There is a need, therefore, for improved arrangements in precision hoe openers that improve the accuracy of the seeding operation. There is a particular need for a precision hoe opener configuration that allows adjustments in the distance between the ground engaging tool and the packing wheel to improve seeding accuracy.